From e852397eaba7bf4f8b69060118374f831216a60e Mon Sep 17 00:00:00 2001
From: Mike Dilger <mike@mikedilger.com>
Date: Sat, 16 Dec 2023 15:17:07 +1300
Subject: [PATCH] Fix a buffer length panic in decryption

---
 src/lib.rs | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 49b1ff4..9dde435 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -165,6 +165,9 @@ pub fn decrypt(conversation_key: &[u8; 32], base64_ciphertext: &str) -> Result<S
     let mut cipher = ChaCha20::new(&keys.encryption().into(), &keys.nonce().into());
     cipher.apply_keystream(&mut buffer);
     let unpadded_len = u16::from_be_bytes(buffer[0..2].try_into().unwrap()) as usize;
+    if buffer.len() < 2 + unpadded_len {
+        return Err(Error::InvalidPadding);
+    }
     let unpadded = &buffer[2..2 + unpadded_len];
     if unpadded.is_empty() {
         return Err(Error::MessageIsEmpty);